"Strained Peas" is the third short story in the book Tales to Give You Goosebumps.
Nicholas isn't excited about the idea of having a baby sister. While he waits for his parents to come home with the baby, he reads an Iron Man comic book where he fights a villain with a "mark of evil", that gives him away. His mother arrives home from the hospital with the baby, Hannah. Nicholas notices that Hannah has a similar mark as the villain in the story, but his parents write it off. Strange things start to happen around the house regarding Hannah. Her eyes change color, her heart-shaped birthmark grows, and she eats his homework. He comes to believe that Hannah is a monster, despite his parents' assurances that there is a perfectly normal explanation for everything.
Things come to a head when Hannah attempts to stab him with scissors but instead Mom scolds Nicholas for allowing her to get near them to begin with. Eventually, it is discovered that while in the hospital, Hannah was accidentally switched at birth with the boy's real sister, and she is not related to him at all. She is returned to the hospital and they get their real baby, who they name Grace. She seems totally normal. When Nick's parents put Grace to bed, Nick gets up to go tickle her. Grace gets angry and says "If you tickle me again kid, I'll rip your arm off!" As Nick flees, he hears her say, "I'll get rid of you creep. Just wait until I can walk!'"
- This story references Iron Man and Volvo.
- Nicholas' mother is mentioned by name in the story: Dori.
- Nicholas is not given a last name in the story but the television episode credits it as Morgan. Morgan was the last name of a babysitter that appears at the start of the story.